infrared dissociation spectra of the phenol-Ar and -Kr van der Waals cluster ions in supersonic free jets were observed in the absorption region of the OH stretching vibration. Both spectra showed the OH stretching vibration at 3535 +/- 2 cm-1, indicating that the perturbation of the rare gases is small and the observed frequency represents that of the bare phenol ion. The vibrational frequency of the phenol ion was found to be 122 cm-1 smaller than that of neutral phenol.